Ugh. It's a bug in SelfLoader. Look for the line that says:

    croak("$callpack doesn't contain an __DATA__ token")
        unless fileno($fh);
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It should say:

    croak("$callpack doesn't contain an __DATA__ token")
        unless defined fileno($fh);
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Notice the "defined" test? In your system (and mine as well), when you close stdin (fileno 0), the C library reuses that file handle for the next usage - which is reading $0, which goes to *main::DATA. So the file number here is 0, which is false, and it croaks. What the author should have said is "check if there is a file number" - not that it's non-zero. (According to fileno, it returns undef if it's not open.)

I suggest opening a bug against it and pointing to this thread. And then you can patch your own if you feel lucky ;-)